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911.
A possibility to prevent collisions with the Earth of dangerous celestial bodies by directing at them small asteroids is considered.
It is proposed to solve this problem using a gravitational maneuver near the Earth. 相似文献
912.
This paper reviews the work carried out at the Atomic Energy Research Establishment (AERE) since 1963 in connection with the development of isotope-powered thermoelectric generators, known as RIPPLEs. It outlines the criteria considered for the selection of strontium 90 as the radioisotope, the design of the generators, the choice of material for the biological shield, and the development of the thermal insulation. It briefly discusses the voltage conversion system employed and states safety design considerations. The paper concludes by discussing the effect of efficiency on the cost of generators and shows typical costs curves. 相似文献
913.
Based on the data of numerical simulation of the test stand gas-liquid ejector operation, the fields of gasodynamic flow parameters in the gas flue channel are determined. The test stand operation in real time and processes of interaction between the flow of combustion products and neutralizing liquid are also analyzed. 相似文献
914.
915.
The concept of “space patrol” is considered, aimed at discovering and cataloging the majority of celestial bodies that constitute
a menace for the Earth [1, 2]. The scheme of “optical barrier” formed by telescopes of the space patrol is analyzed, requirements
to the observation system are formulated, and some schemes of sighting the optical barrier region are suggested (for reliable
detection of the celestial bodies approaching the Earth and for determination of their orbits). A comparison is made of capabilities
of electro-jet engines and traditional chemical engines for arrangement of patrol spacecraft constellation in the Earth’s
orbit. 相似文献
916.
William F. Dempster 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
Processes which produce slow changes in air composition in a closed ecological system (CES) may not be noticed if the leak rate of the CES is significant. Dilution of the system’s air with outside air can mask these processes. A tightly closed CES provides the opportunity for slow changes to accumulate over time and be observed and measured. Biosphere 2 (volume 200,000 m3) had a low leak rate of less than 10 percent per year. Oxygen declined slowly at varying rates reflecting seasonal influences, which averaged to about 140 ppm per day during the first 16 months of the two-year closure. Computer simulations of the observed rate of oxygen loss combined with other hypothetical leak rates suggest that the decline would have been hidden by a leak rate as low as one percent per day. Sealing Biosphere 2 involved rigorous design specifications and inclusion of two expansion chambers (called “lungs”) to accommodate expansion/contraction of the atmosphere, which enabled limiting the pressure difference between inside and outside atmospheres to the range of ±8 Pa (0.08 mBar). Measurement of leak rate was by two methods: the first, measuring the rate of deflation of the lungs while holding a constant elevated pressure differential enabled calculation of an estimated leak rate within the usual operating pressure differential range; the second was to measure the progressive dilution of trace gases spiked into the atmosphere. Both methods confirmed leakage to be less than 10 percent per year. Operational data from the 40 m3 Laboratory Biosphere is used to illustrate how normal variations of temperature, humidity and barometric pressure would combine to force leakage and rapidly dilute the internal atmosphere if it were not equipped with a lung. It is demonstrated that very high degrees of closure for a CES enable experimental observation of small imbalances in atmospheric cycles or slow accumulation of trace gases that could otherwise be masked by dilution with atmosphere external to the CES. 相似文献
917.
Translational-rotational motion of three planets modeled by viscoelastic balls in the gravitational field of mutual attraction
is studied in this paper. The system of equations of motion for the mechanical system under consideration is deduced from
the d’Alembert-Lagrange variational principle. Using the method of separation of motions, an approximate system of ordinary
differential equations, describing the translational-rotational motion of the planets, is obtained with taking into account
perturbations caused by elasticity and dissipation. The found steady-state motion of the system is an analog to triangular
libration points in the classical three-body problem. 相似文献
918.
N. A. Vlasova N. N. Pavlov M. I. Panasyuk N. N. Vedenkin T. A. Ivanova G. P. Lyubimov S. Ya. Reizman V. I. Tulupov 《Cosmic Research》2011,49(6):485-499
We compared fluxes of the 1–100 MeV solar energetic particles (SEP) measured in the interplanetary medium (ACE) and in the magnetosphere (Universitetsky-Tatiana, POES—in polar caps, and GOES-11—at geosynchronous orbit) during several SEP events of 2005–2006. Peak intensities of the SEP fluxes inside and outside the
magnetosphere were compared for each event. It is shown that observed inside-outside difference depends mainly on direction
of interplanetary magnetic field (IMF), on degree of the SEP anisotropy (pitch-angle distribution) in IMF, and on distance
of the dayside magnetopause from the Earth. 相似文献
919.
920.